a. Field of the Invention
The invention relates to agents for the care of the skin which are distinguished by proven efficacy for their purpose.
B. Prior Art
In cosmetology there are employed finished products or active substances whose purpose is to produce a revitalizing or rejuvenating effect on the skin. The terms "revitalizing" or "rejuvenating" are used generally and the contention that a revitalizing effect is achieved is generally not supported by reproducible, pharmacological proof.
It is known from gerontological research (Bjorksten) that the process of aging of the skin takes place mainly at the connective tissue of the cutis. This corium (85% of the skin thickness located under the epidermis) consists substantially of three-dimensionally intertwined collagenous fibres the chemical units of which are mainly monoamino acids. In the useful fibers, there is principally soluble collagen. In aging skin, the soluble collagen becomes insoluble, inelastic and rigid and is accompanied by the formation of intermolecular and interamolecular crosslinkings. As the skin ages the proportion of insoluble collagen increases, at the expense of the soluble collagen; the aging skin loses its resilience and therewith its water absorptivity and swelling capability.
The physiological aging process in the skin i.e., increase in insoluble collagen due to increased crosslinking, has an influence on cosmetics of entirely decisive importance. The skin loses its elasticity and its ability to swell due to its reduced water-binding capacity. It is true that the diminution in respect of soluble collagen is a physiological process forming part of the aging process but, from the cosmetic viewpoint, it is extremely undesirable.
The natural aging process is further accelerated, due to the influence of light and in particular of the sun, especially skin which is exposed to the action of light (the face, the neck and the hands). Soluble collagen is rapidly lost in skin subjected to the action of light (Shuster and Bottons). This makes the loss of resilience especially obvious. The skin becomes "leathery" and acquires an increased quantity of creases and wrinkles, because the water-binding capacity has been lost.
German Pat. No. 1,194,098 discloses a cosmetic agent for improving the skin turgor containing, in the cosmetic base, 3 to 15% by weight of a gelatine obtained from collagen and having a thixotropic resistance of below approximately 80 g Bloom and viscosity below approximately 20 m P.
However, the agent is intended to serve for improving the elasticity of the skin, since the collagen has, due to the processing necessary for converting it to a gelatine of the type specified, lost its specific resilience-promoting properties. Thus, such hydrolyzates are unsuitable for rejuvenation of the skin. The denatured, aged collagens are not utilized by the organism.